Identifying the genetic basis of disease

It is all in the DNA. Our genetic code, or genotype influences much about us. Not only are physical attributes (appearance, height, weight, eye color, hair color, etc.), all fair game for genetics, but also possibly more important things like our susceptibility to diseases, response to a certain drug, and so on. We refer to these ‘observable physico-chemical traits’ as phenotypes. Note that ‘to influence’ is not the same as ‘to determine’ other factors such as the environment one grows up in can play a role. The exact contribution of the genotype in determining a specific phenotype is a subject of much research. The best we can do today is to measure correlations between the two. Even this simpler problem has many challenges. But we are jumping ahead of ourselves. Let us review some biology.